Alternating Dual Polarization OFDM PAPR Reduction
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Solution Overview
Problem
Conventional OFDM systems face issues with high peak-to-average power ratio (PAPR), expensive oscillator requirements, increased sensitivity to oscillator phase noise, and susceptibility to intercarrier interference (ICI) due to Doppler effects.
Innovation Solution
The implementation of Alternating Dual Polarization States (ADPS)-OFDM, where subcarriers are transmitted using alternating horizontal and vertical polarizations, reducing PAPR, allowing for less expensive oscillator components, and providing enhanced immunity to ICI through increased subchannel spacing and additional interleaving.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional OFDM is used with multiple subcarriers, then data transmission capacity is improved, but peak-to-average power ratio increases
Solution Approach 1:
The patent segments the OFDM signal into multiple polarized components (e.g., horizontal and vertical polarizations). Each segmented signal has a lower PAPR than the composite signal, allowing more efficient power amplification while maintaining the total data transmission capacity through combination of the segmented channels.
2Productivity
If the number of subcarriers is increased for a given bandwidth, then data rate is improved, but oscillator phase noise requirements become more stringent
Solution Approach 1:
The patent divides the high-subcarrier system into multiple polarized sub-systems with fewer subcarriers each. This segmentation relaxes the phase noise requirements for each oscillator while maintaining the overall data rate through the combined capacity of multiple polarized channels.
3Productivity
If subcarriers are closely spaced to increase bandwidth efficiency, then spectral efficiency is improved, but susceptibility to intercarrier interference increases
Solution Approach 1:
The patent introduces polarization as an additional dimension for signal separation. By encoding data across multiple polarized dimensions rather than relying solely on frequency separation, the system can use closer subcarrier spacing while maintaining immunity to intercarrier interference through the orthogonal polarization states.
Data Source
AI summary
An Orthogonal Frequency Division Multiplexer (OFDM) transmitter and receiver apparatus consistent with certain embodiments of the present invention receives data to be transmitted and maps (204) a first portion of the data to a first polarization state and a second portion of the data to a second polarization state. A first transmitter (216) transmits the first portion of the data as a set of first OFDM subcarriers using an antenna (230) exhibiting a first polarization. A second transmitter (234) transmits the second portion of the data as a set of second OFDM subcarriers using an antenna (240) exhibiting a second polarization, wherein the first polarization is orthogonal to the second polarization. A receiver apparatus uses a first antenna (302) exhibiting the first polarization and a second antenna (306) exhibiting the second polarization. A first OFDM receiver (310) receives a first set of polarized OFDM subcarriers from the first antenna (302) while a second OFDM receiver (324) receives a second set of polarized OFDM subcarriers from the second antenna (306). A decoder (330) decodes the first and second sets of OFDM subcarriers and combines them into a stream of data.